Neural crest specification by Max’s giant associated protein and regulation of microtubule’s function by alpha-tubulin acetyltransferase 1 in zebrafish
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During the embryonic development of vertebrates, progenitor cells receive guidance and start to proliferate, differentiate, and migrate to form various tissues and organs. This process requires the coordination of cell signaling, transcriptional regulation, and cytoskeleton reorganization. In this study, we focus on understanding the roles of two different proteins, Max’s giant associate protein (Mga) and α-tubulin acetyltranferase 1(ATAT1), in zebrafish development. It has been suggested that Mga is a Myc antagonist and participates in activating the expression of bmp2b in the yolk syncytial layer (YSL) of zebrafish. Here we show that Mga plays a novel role in regulating neural crest development in zebrafish. Suppressing the expression of Mga by antisense morpholino oligonucleotides leads to various developmental defects in zebrafish embryos. Most cell lineages that derive from neural crest are affected in mga morphants, suggesting that Mga might play a role in maintaining the normal formation of neural crest cell population. Mga might control neural crest formation by positively regulating BMP signaling, or alternatively, by antagonizing the activity of Myc. To understand more about the mechanism, we further targeted mga with RGN system and identified five different potentially null alleles. Further characterization of mga mutants is required to understand the function of Mga. ATAT1 is the major α-tubulin acetyltransferase responsible for tubulin acetylation, a conserved tubulin post-translational modification (PTM) associated with stable microtubules, in ciliates, worms, and mice. Here we employed TALENs to target zebrafish atat1 and successfully generated two atat1 null mutants. atat1 mutants deplete acetylated α-tubulin completely in microtubules, suggesting that ATAT1 is also the major α-tubulin acetyltranferase in zebrafish. atat1 mutants are viable, fertile, and exhibiting no overt developmental defect. However, atat1 mutant embryos are more sensitive to Paclitaxel treatment. Furthermore, several tubulin PTMs are altered in atat1 mutants. Tubulin monoglycylation is elevated in atat1 mutants. Severe cilia-related defects are observed in zebrafish embryos void of both ATAT1 and tubulin monoglycylase TTLL3. This result suggests a possible interaction among different tubulin PTMs.